When bare soil is exposed between crops, carbon stored in the soil is lost to the atmosphere. By planting cover crops on croplands that have an off-season fallow period, farmers can expand the length of time that photosynthesis occurs on cropland. This practice, also known as conservation agriculture, increases the amount of carbon stored in the soil, while also improving soil quality and fertility.
About 350 million hectares – up to 25 percent of the world’s cropland – could be planted with cover crops. That’s an area six times the size of Texas.
Practicing conservation agriculture could sequester up to 372 million tonnes of carbon dioxide equivalent per year (MtCO2e/year). That’s comparable to the emissions from 79 million passenger vehicles per year.
Cover crops have the potential to improve soil fertility, increase yields and retain soil moisture to mitigate the effects of drought. However, more research is needed to fully demonstrate that those benefits can consistently offset the costs of planting cover crops.
One of the challenges to conservation agriculture will be disseminating knowledge to farmers about what type of cover crop or crop mixture to plant, when to plant, how deeply to plant and, in some cases, what new equipment might be necessary. Already, many farming groups and conservation groups are actively educating farmers about the use of cover crops, but more effort will be needed to spread that knowledge to growers around the world.
Cover crops aren’t suitable everywhere, such as in some areas in the tropics that are already double-cropped. However, this pathway could be applied to many croplands around the globe.
Conservation agriculture is a low-cost pathway that can be implemented by farmers relatively quickly and easily as part of their standard business practice. Indeed, many farmers are already successfully using cover crops today.
Spotlight: Soil Health Partnership
Healthy soils are critical for higher yields, and healthy soils benefit the environment as well. Farmers know that better than anyone, and across the United States many farmers are implementing new management practices to improve their soils. In the U.S, the Soil Health Partnership is building upon that work to identify, test, and measure management practices to improve soil health, while benefiting the environment and farmers’ bottom lines.
The partnership is an initiative of the National Corn Growers association, with support from a variety of corporations and organizations including The Nature Conservancy. The project promotes planting cover crops, among other management strategies, on its research and outreach farms across the US Midwest. The ultimate goal is to measure and communicate the economic and environmental benefits of different soil management strategies, providing a set of regionally specific, science-based recommendations that will guide farmers to improve both productivity and sustainability on their lands.
Similar efforts to improve soil health through cover crops could be used on croplands around the world.